Exploring the impact of stage and tumor site on colorectal cancer survival: Bayesian survival modeling.

Colorectal cancer is a prevalent malignancy with global significance. This retrospective study aimed to investigate the influence of stage and tumor site on survival outcomes in 284 colorectal cancer patients diagnosed between 2001 and 2017. Patients were categorized into four groups based on tumor site (colon and rectum) and disease stage (early stage and advanced stage). Demographic characteristics, treatment modalities, and survival outcomes were recorded. Bayesian survival modeling was performed using semi-competing risks illness-death models with an accelerated failure time (AFT) approach, utilizing R 4.1 software. Results demonstrated significantly higher time ratios for disease recurrence (TR = 1.712, 95% CI 1.489-2.197), mortality without recurrence (TR = 1.933, 1.480-2.510), and mortality after recurrence (TR = 1.847, 1.147-2.178) in early-stage colon cancer compared to early-stage rectal cancer. Furthermore, patients with advanced-stage rectal cancer exhibited shorter survival times for disease recurrence than patients with early-stage colon cancer. The interaction effect between the disease site and cancer stage was not significant. These findings, derived from the optimal Bayesian log-normal model for terminal and non-terminal events, highlight the importance of early detection and effective management strategies for colon cancer. Early-stage colon cancer demonstrated improved survival rates for disease recurrence, mortality without recurrence, and mortality after recurrence compared to other stages. Early intervention and comprehensive care are crucial to enhance prognosis and minimize adverse events in colon cancer patients.

The prophylactic effect of photobiomodulation therapy on pain perception due to infiltration injection: a randomized clinical trial.

OBJECTIVES: Fear of pain in dentistry especially the injection involved in most of the processes has always been an important issue preventing the patients from consulting a dentist at the right time. This study aims to evaluate the effect of photobiomodulation therapy on reduction of pain in infiltration injection. MATERIALS AND METHODS: This trial is a crossover study including 30 patients. The patients are divided into two groups (laser therapy in the first period and placebo effect in the next period or vice versa with split-mouth design) using the covariate adaptive randomization method. All the patients received bilateral maxillary canine anesthesia in two periods performed with an ICT injection device (amount of anesthesia solution loaded: 1.8 mL) at a speed of 1 mL/min and a temperature of the solution of 37 °C. In each period, patients received either a prophylactic dose of 940-nm laser (500 mW, 10 J/cm2) or its placebo effect before the injection. The degree of pain perception after each sort of treatment is evaluated by both SEM (Sound, Eye, Motor, and Pain) and VAS (Visual Analogue Scale) scales. RESULTS: According to analysis, all the patients scored a VAS scale under 3 in the period they received intervention. Also considering the SEM scale, most of the patients scored 0 in the intervention period. No adverse effect was reported during or after the process. CONCLUSIONS: The study showed a significant effect of photobiomodulation on reducing pain perception during infiltration injection. CLINICAL RELEVANCE: This method can be useful in order to lower the pain for the patients consulting a dentist and therefore facilitate consulting at early stages of the dental issues. TRIAL REGISTRATION: The registration number (date) of the clinical trial in a Primary Registry in the WHO Registry Network is IR.ARAKMU.REC.1398.248(13/03/2020). The related URL is https://en.irct.ir/trial/45362 .

Estimation of treatment effect in presence of noncompliance and competing risks: a simulation study.

A randomized controlled trial is commonly designed to assess the treatment effect in survival studies, in which patients are randomly assigned to the standard or the experimental treatment group. Upon disease progression, patients who have been randomized to standard treatment are allowed to switch to the experimental treatment. Treatment switching in a randomized controlled trial refers to a situation in which patients switch from their randomized treatment to another treatment. Often, the switchis from the control group to the experimental treatment. In this case, the treatment effect estimate is adjusted using either convenient naive methods such as intention-to-treat, per-protocol or advanced methods such as rank preserving structural failure time (RPSFT) models. In previous simulation studies performed so far, there was only one possible outcome for patients. However, in oncology in particular, multiple outcomes are potentially possible. These outcomes are called competing risks. This aspect has not been considered in previous studies when determining the effect of a treatment in the presence of noncompliance. This study aimed to extend the RPSFT method using a two-dimensional G-estimation in the presence of competing risks. The RPSFT method was extended for two events, the event of interest and the competing event. For this purpose, the RPSFT method was applied based on the cause-specific hazard approach, the result of which is compared to the naive methods used in simulation studies. The results show that the proposed method has a good performance compared to other methods.

Recurrence and Postoperative Death in Patients with Colorectal Cancer: A New Perspective via Semi-competing Risk Framework.

BACKGROUND/AIMS: Cancer studies suffer from an overestimation of prediction of survival when both recurrence and death are of interest. This longitudinal study aimed to mitigate this problem utilizing a semi-competing risk approach evaluating the factors affecting recurrence and postoperative death in patients with colorectal cancer. MATERIALS AND METHODS: This longitudinal prospective study was conducted in 284 patients with resected colorectal cancer who were referred to the Imam Khomeini Clinic in Hamadan, Iran, during 2001-2017. Primary outcomes were postoperative outcomes and patient survival, including time to recurrence (of colorectal cancer), time to death, and time to death after recurrence. All patients who were alive at the end of the study were censored for death and who did not experience recurrence of colorectal cancer were also censored for recurrent colorectal cancer. The relationship between underlying demographics and clinical factors and the outcomes was assessed using a semicompeting risk approach. RESULTS: The results of the multivariable analysis showed that having metastasis to other sites (hazard ratio = 36.03; 95% CI = 19.48- 66.64) and higher pathological node (pN) stage (hazard ratio = 2.46; 95% CI = 1.32-4.56) were associated with a raised hazard of recurrence. The fewer chemotherapies (hazard ratio = 0.39; 95% CI = 0.17-0.88) and higher pN stages (hazard ratio = 4.32; 95% CI = 1.27-14.75) showed significantly higher hazards of death without recurrence. Having metastasis to other sites (hazard ratio = 2.67; 95% CI = 1.24-5.74) and higher pN stages (hazard ratio = 1.91; 95% CI = 1.02-3.61) were linked with the higher hazard of death after recurrence. CONCLUSION: Considering findings on death /recu rrenc e-spe cific predictors obtained in this study to manage the outcomes in patients with colorectal cancer, tailored strategies for preventive and interventional plans should be deliberated.

Perception of laypersons, orthodontists, and oral and maxillofacial surgeons about the transverse occlusal plane.

INTRODUCTION: Transverse occlusal plane (TOP) should be parallel to the true horizontal lines of the face (ie, the interpupillary line [IP] and commissural line [CL]). This study aimed to investigate the opinions of laypersons, orthodontists, and oral and maxillofacial surgeons about the impact of imbalanced IP and CL on facial attractiveness. METHODS: We used a symmetrical face image as the reference. Then, using Photoshop software, we constructed the following 6 photographs: TOP roll relative to CL and IP (3° and 6°) with parallelism of CL and IP, CL roll relative to TOP and IP (3° and 6°) with parallelism of TOP and IP, TOP and CL roll relative to IP (3° and 6°). Consequently, the participants rated the photographs on the basis of their attractiveness. Kruskal-Wallis and Mann-Whitney U tests were used to compare the ratings. RESULTS: One hundred thirty-one laypersons, 22 orthodontists, and 20 surgeons participated in this study. It was found that 51.1% of laypersons, 86.4% of orthodontists, and 70% of surgeons selected the reference photograph as the most beautiful, followed by the photograph with a 3° roll of CL relative to TOP, with parallelism of TOP and IP (29% of laypersons, 31.8% of orthodontists, and 35% of surgeons). CONCLUSIONS: Most participants selected the reference photograph as the most beautiful and realized a roll in the horizontal planes up to 3°. The parallelism of the esthetic line of dentition relative to interpupillary is preferred over its parallelism relative to CL.

Influential Factors on Survival in Gastric Cancer: A Single-center Study.

Background: Gastric cancer (GC) is one of the conspicuous causes of cancer-related death worldwide. Considering the mounting incidence of this cancer in developing countries such as Iran, determining the influential factors on the survival of involved patients is noteworthy. Hence, we aimed to ascertain the survival rates and the prognostic factors in our GC patients. Materials and Methods: In this retrospective cohort study, data of 314 patients with GC in a referral cancer center in Hamadan province of Iran were studied. The outcome of our study was survival time and the influential factors were gender, age at diagnosis, tumor history, tumor grade, surgery history, radiotherapy history, stage of disease, metastasis history, and lymph node involvement. Kaplan - Meier method and log-rank test were used for the calculation and comparing the survival curves and Cox-proportional hazard model was used for the multivariable analysis of prognostic factors. Results: In a total of 314 GC patients, the median age at the diagnosis was 63 years (range: 21-92) with most patients (74.84%) being males. The median follow-up time was 2.42 years, and the median survival time was 2 years. The multivariable cox analysis of overall survival (OS) indicated that having distant metastasis increased the hazard of death by about 2.5 times (P < 0.0001, heart rates [HR]: 2.53, 95% confidence interval [CI]: [1.71, 3.75]), and receiving surgery as treatment, decreased the hazard of death up to 36% (P = 0.02, HR: 0.64, 95%CI: [0.46-0.89]). The other variables did not have any significant effects on the OS. Conclusion: The results of this study showed that lower survival (greater hazard of death) strongly and significantly associated with having distant metastasis in patients with GC and receiving surgery could significantly decrease the hazard of death in these patients instead.

In Vitro Effect of a High-Intensity Laser on Candida albicans Colony Count.

Introduction: This study assessed the effect of a high-intensity laser on Candida albicans colony count. Methods: This in vitro, experimental study was conducted on standard-strain C. albicans (ATCC18804). Seventy-two samples with two different concentrations of C. albicans (104 cells/mL and 106 cells/mL) were randomly assigned to three groups of control, laser and nystatin. Each group included 12 samples from each concentration. In the nystatin group, 10 cc of nystatin suspension was added to the samples and mixed for 30-60 seconds. In the laser group, the Ga-Al-Ar diode laser with a 940-nm wavelength and 2-W power was irradiated to the samples with 0.4 mm tip diameter in non-contact mode (1-mm distance) at a speed of 1 mm/s. The suspensions in the three groups were cultured on the Sabouraud dextrose agar culture medium and incubated at 37°C for 24 hours. The number of C. albicans colonies was then counted and reported. The three groups were compared by ANOVA and Tukey's test (alpha=0.05). Results: In both concentrations, the mean colony count in the nystatin group was significantly lower than that in the control (P<0.05) and laser (P<0.05) groups. The mean colony count in the laser group was significantly lower than that in the control group (P<0.05). Conclusion: The high-intensity laser with a 940-nm wavelength and 2-W power in non-contact mode can significantly decrease the C. albicans colony count in vitro, but its effect is lower than that of nystatin.

Factors affecting the survival of patients with colorectal cancer using random survival forest.

PURPOSE: Colorectal cancer is one of the most common cancers and the leading cause of cancer death in Iran. This study aimed to develop and validate a random survival forest (RSF) to identify important risk factors on mortality in colorectal patients based on their demographic and clinical-related variables. METHODS: In this retrospective cohort study, the information of 317 patients with colorectal cancer who were referred to Imam Khomeini Clinic of Hamadan during the years of 2002 to 2017 were examined. Patient survival was calculated from the time of diagnosis to death. In the present study, the RSF model was used to identify factors affecting patient survival. Also, the results of the RSF model were compared with the Cox model. The data were analyzed using R software (version 3.6.1) and survival packages. RESULTS: One-, 2-, 3-, 4-, 5-, and 10-year survival rates of included patients were 81.4%, 63%, 57%, 52%, 45%, and 34%, respectively, and the median survival was obtained to be 53 months. The number of 150 patients was died at this time period. The four most important predictors of survival included metastasis to other organs, WBC count, disease stage, and number of lymphomas involved. RSF method predicted survival better than the conventional Cox proportional hazard model. CONCLUSION: We found that metastasis to other organs, WBC count, disease stage, and number of lymphomas involved were the most four most important predictors of low survival for colorectal cancer patients.

Determining the Risk Factors Affecting on Death Due to Colorectal Cancer Progression: Survival Analysis in the Presence of Competing Risks.

PURPOSE: In survival analysis, some patients may be at risk of more than one event, for example cancer-related death and cancer-unrelated death. In this case, if the aim of study becomes to assess the impact of risk factors on different causes of death, the competing risk model should be used rather than classical survival model. The aim of the present study is to determine the risk factors for related and unrelated mortality in patients with colorectal cancer using competing risk regression models. METHODS: The present retrospective cohort study was carried out on 310 CRC patients. Death due to cancer progression was considered as the interest event, and death due to unrelated cancer was considered as a competing event. Two most popular methods, cause-specific and subdistribution hazard regression model, were used to determine the effect of covariates on incidence and cause-specific hazard. Data analysis was performed using R3.6.2 software and cmprsk and survival packages. RESULTS: The mean (SD) of patients' age was 55.84 ± 13.2 years and 53.9% of them were male. BMI, T and N stage had a significant effect on both incidence and cause specific hazard of cancer-related death. CONCLUSION: The results of this study showed that cancer-related death is strongly correlated with under-weight (BMI < 18.5) and advanced clinical stage of the disease in patients with colorectal cancer. So, in the presence of competing events, both types of regression hazard models should be applied to permit a full understanding of the impact of covariates on the incidence and the rate of occurrence of each outcome.

Identifying the Risk Factors for Mortality in Patients with Cancer and COVID-19 in Hamadan, the West of Iran.

PURPOSE: Since cancer patients are at higher risk of COVID-19, the present study was conducted to investigate the epidemiology of these patients and identify the affecting risk factors on their mortality. METHODS: The present retrospective cohort study was conducted on 66 hospitalized patients with cancer and COVID-19 in Hamadan in 2020. In the present study, demographic, clinical, and laboratory information and patients' outcome were collected through a checklist and its impact on death was assessed. Data were analyzed in SPSS-24 software and the significance level of the tests was considered at 5%. RESULTS: The mean (standard deviation (SD)) age of patients was 61.6 (13.5) years. Forty patients (60.6%) were male. Twenty and five patients (37.9%) died at the end of study. The results of logistic regression model revealed that the nausea, mechanical ventilation, admission to ICU, and length of hospital stay in the ward had a significant impact on the odds of death among cancer patients with COVID-19 (p < 0.05). CONCLUSION: Owing to high mortality rate in cancer patients with COVID-19 and due to underlying diseases and more severe clinical symptoms than other patients with coronavirus, these patients need intensive care and specific treatments. However, screening these patients and early identifying and vaccinating of them can reduce the mortality rate in these patients.

Factors related to mortality due to progression of disease in patients with colon cancer in the presence of competing risks: a retrospective cohort study in the west of Iran.

AIM: This study aims to identify the risk factors of disease-related death in patients with colon cancer in the presence of competing risks. BACKGROUND: Competing risk analysis is an effective method for identifying risk factors of death from disease, and the evidence related to the prognosis of death in patients with colon cancer in the country is rare. METHODS: In this historical cohort study, the information of 196 patients with colon cancer who were referred to Imam Khomeini Clinic in Hamadan during the years 2003 to 2017 were examined. Death due to the progression of cancer was considered an interesting cause, and death related to other causes was considered a competing event. Predictors of death due to the progression of cancer were determined in the presence of competing risks. The cause-specific hazard regression model was used to determine the effects of covariates. Data was analyzed using R software vol. 3.4.3 and survival packages. RESULTS: The mean (SD) age of patients was 57.1 (12.9) years, and 52.6% were male. The results of the multivariate cause-specific hazard regression model showed that the patient's age at the time of cancer diagnosis, T stage, stage of the disease and N stage had significant effects on the hazard of death due to cancer progression (p<0.05). CONCLUSION: In the presence of various causes of death, using the cause-specific hazard model to identify the risk factors of each cause separately can better support clinical decisions compared to other models.

Estimating the treatment effect in patients with gastric cancer in the presence of noncompliance.

AIM: In this study, these methods were used to estimate the treatment effect in patients with gastric cancer in the presence of noncompliance. BACKGROUND: In medical sciences, simple and advanced methods are used to estimate treatment effects in the presence of noncompliance. METHODS: This historical cohort study surveyed 178 patients with gastric cancer underwent chemotherapy alone (chemotherapy alone group) and 193 patients underwent surgery and chemotherapy (surgery plus chemotherapy group) from 2003 to 2007 at the Cancer Institute of Imam Khomeini Hospital (Tehran). Demographic and clinical characteristics were extracted from patients' hospital records. The survival of patients was calculated as being from diagnosis to death or to the end of the study. The treatment effect was estimated using three methods: treatment as a time-dependent covariate, IPCW, and Structural Nested Models using STATA and R software. RESULTS: Fifty-six patients (31.5%) who underwent chemotherapy and 69 patients (35.8%) who underwent surgery and chemotherapy died by the end of the study. The hazard ratio in group I compared to group II was estimated between 1.5 to 2.07 times based on the simple analysis method. The modified hazard ratio was estimated to be 1.21 (95% CI: 1.11-1.32) based on the SNM method. Surgery plus chemotherapy is superior to chemotherapy alone, and it improves the overall survival (OS) rate of gastric cancer patients. CONCLUSION: Survival was improved in patients undergoing chemotherapy and surgery together compared to those undergoing chemotherapy alone. The results of the current study suggest that treatment effect can be estimated unbiasedly using the appropriate method.

Specific causes of recurrence after surgery and mortality in patients with colorectal cancer: A competing risks survival analysis.

BACKGROUND: In situation where there are more than one cause of occurring the outcome such as recurrence after surgery and death, the assumption of classical survival analyses are not satisfied. To cover this issue, this study aimed at utilizing competing risks survival analysis to assess the specific risk factors of local-distance recurrence and mortality in patients with colorectal cancer (CRC) undergoing surgery. MATERIALS AND METHODS: In this retrospective cohort study, 254 patients with CRC undergoing resection surgery were studied. Data of the outcome from the available documents in the hospital were gathered. Furthermore, based on pathological report, the diagnosis of CRC was considered. We model the risk factors on the hazard of recurrence and death using competing risk survival in R3.6.1 software. RESULTS: A total of 114 patients had local or distant recurrence (21 local recurrences, 72 distant recurrences, and 21 local and distant recurrence). Pathological stage (adjusted hazard ratio [AHR] = 4.28 and 5.37 for stage 3 and 4, respectively), tumor site (AHR = 2.45), recurrence (AHR = 3.92) and age (AHR = 3.15 for age >70) was related to hazard of death. Also based on cause-specific hazard model, pathological stage (AHR = 7.62 for stage 4), age (AHR = 1.46 for age >70), T stage (AHR = 1.8 and 2.7 for T3 and T4, respectively), N stage (AHR = 2.59 for N2), and white blood cells (AHR = 1.95) increased the hazard of recurrence in patients with CRC. CONCLUSION: This study showed that older age, higher pathological, rectum tumor site and presence of recurrence were independent risk factors for mortality among CRC patients. Also age, higher T/N stage, higher pathological stage and higher values of WBC were significantly related to higher hazard of local/distance recurrence of patients with CRC.